1. Field of the Invention
This invention relates to a mount structure for electronic circuit packages, and more particularly, to a double type mount structure for mounting thereon a large number of such packages.
2. Description of the Related Art
Generally, a box-shaped shelf used for an electronic switching apparatus is opened at the front thereof, so that the electronic circuit packages can be loaded on and unloaded from the shelf through the front opening.
Recently, to improve the mounting capacity for these electronic circuit packages, it has been proposed that the shelf is divided to two sub-units, i.e., a front unit and a rear unit.
However, in case of dividing one shelf to a front unit and a rear unit for mounting the electronic circuit packages, when the packages in the back unit are to be unloaded from the shelf, the packages in the front unit must be removed in advance from the shelf, as well as an upright back wiring board of the front unit for supporting the electronic circuit packages in the shelf must also be removed so as to open the passage, through which the packages in the rear unit are unloaded, which is very troublesome and requires a lot of time.